In recent years, a therapy method for cancer by high-energy carbon ion irradiation has been developed and a therapy using an ion source that generates an ion beam has been disclosed.
For advanced performance improvement of the ion source, a high-density C6+ needs to be generated. However, for example, since an ion source using μ-wave discharge plasma is lack of capability to generate the high-density C6+, development of a new ion source is required.
Therefore, a laser ion source having an ability to generate a high-density ion beam has been known. The laser ion source is a device that collects and irradiates a laser beam onto a solid target set in a space that satisfies a predetermined vacuum condition, ionizes the solid target by energy of the laser beam, and electrostatically extracts the ions to generate an ion beam.
A feature of the laser ion source is that the solid target is used as a generation source of the ion. By using the solid target as such, high-density ion current can be extracted in the laser ion source.
However, in the case where the laser ion source is continuously operated, the generation source of the ion (that is, the solid target) needs to be supplied in the laser ion source.
For example, in the ion source using the discharge plasma, gas may be just supplied as the generation source of the ion. In this regard, in the laser ion source, the solid target is generally supplied (exchanged) by releasing the laser ion source to the atmosphere whenever supplying the generation source of the ion (that is, the solid target).
When the laser ion source is applied to a medical service, since a long stabilizing operation is required for the corresponding laser ion source, the target is required to be supplied (exchanged) without damaging the vacuum condition in the space where the solid target (hereinafter, simply referred to as a target), which is the ion generation source is set.
In other words, it is important to establish a consecutive supply method of the target which does not significantly damage the vacuum condition in the laser ion source.
However, when the laser ion source is released to the atmosphere whenever supplying the target, the vacuum condition in the space, where the target is set, is damaged.
Therefore, in the laser ion source, a special device is required to supply the target.